Defocus (DIMS) Spectacles Versus Ortho-K Lenses (OKL) for Slowing Myopia Progression in Children Aged 6-12 Years.

Inclusion criteria: \- Myopic children aged 6 to 12 years: Myopia of the 6 to 8-year-olds (inclusive): -1.00 to -4.75 D spherical component and up to -2.50 D of regular astigmatism (both eyes). Myopia of the 9 to 12-year-olds (inclusive): -2.00 to -4.75 D spherical component and up to -2.50 D of regular astigmatism (both eyes). * Anisometropia ≤ 1.50 D cycloplegic spherical equivalent refractive error. * Best corrected visual acuity at age 6 to 12 years (inclusive): 0.8 Snellen (equivalent to ≥ 3/5 letter on the 0.8 line = 78 ETDRS letters) Exclusion criteria: * Manifest or intermittent squint. * Contraindications to the use of OKL comprising (not exhaustive): keratoconus, chronic allergic conjunctivitis and keratoconjunctivitis sicca. * Previous eye surgery. * Chronic eye disease demanding daily use of eye drops. * Non-compliance to eye examinations (unstable fixation or anxiety towards contact lenses). * Previous myopia control treatment.